DE3012332A1 - FINE-POLISHING SUSPENSION AND METHOD FOR PRODUCING THE SAME - Google Patents

Description

Applicant: La Pierre Synthetique Baikowski, S.A.

13, Avenue Des Romains, 74001 Annecy Cedex, France

Fine polishing suspension is a method of manufacture the same.

The invention relates to a permanent, liquid fine polishing suspension and a method for making the same, particularly permanent suspensions of fine polishing articles in non- drying, non-toxic and thickened glycerine-based media.

Polishing, as the shape of the L4 |? Pen, essentially includes the Use of abrasive substances under pressure against the surface of an object to be polished to achieve a relatively smooth finish to obtain. On the other hand there is grinding, which is the other form of lapping and which is mainly abrasion of a substantial portion of a surface and rough unevenness therein, while polishing involves removing finer or even microscopic bumps.

Polishing and grinding are commonly used executed by lapping agents, which are made of relatively small inorganic sand particles serving as an abrasive agent, as well as from a Carrier medium consist / in which these particles are contained. the The size of the sand particles used in principle determines the smoothness of the surface finish, with 10 microns being the usual grain size represents between grinding and polishing. The fine polishing of materials such as optical parts, plastics, metals, precious stones, Semiconductors and the like, usually requires the

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need of even finer abrasive sand particles and includes partially unsolved problems.

Typically contained heretofore in use with fine polishing lapping agents used suspensions of very fine, abrasive sand particles (less than 5 microns in size). However, it was very difficult to make the abrasive particles more homogeneous To keep the suspension in the carrier, especially in view of the relatively small number of abrasive particles in the Relation to the large proportion of the carrier medium in such a medium.

This problem is particularly noticeable when using water as a carrier medium which, on the one hand, is readily available and inexpensive as a general medium, but on the other hand is a suspension revealed in which the abrasive particles mixed in it precipitated very quickly and settled on the bottom of the container. Also, aqueous suspensions are subject to relatively rapid moisture loss during their use, which is why frequent additives further liquid made necessary during the polishing process in order to obtain the desired properties of the polishing agent. Oil has occasionally been used as a carrier medium for a polishing suspension, but this is not particularly desirable because of the problems affecting the lapping tool and the workpiece and the tendency of the oil to rinse during the polishing process, as well as because of the inconsistency of the suspension.

Fine polishing agents were recently introduced, which are the main

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component or as the basis of the carrier medium di-hydroxide-glycol (such as ethylene glycols). In connection with the glycol base, which is a glycol / water mixture, with one opposite water The higher percentage of glycol by weight was a small amount of carboxy-polymethylene polymer of high molecular weight added to the carrier medium to thicken the polishing agent and the abrasive Better to keep particles in suspension. In the preparation of such compounds it was necessary to use the acid-forming polymer add a neutralizing agent to achieve the appropriate viscosity of the carrier medium.

Such glycol-based compounds were the water-based compounds in terms of durability of the suspension and dehydration resistance, but they could not fully remedy the pre-existing shortcomings and, in fact, have produced other undesirable properties. For example, glycols are generally poisonous Substances, so that in the polishing process carried out using glycol-based polishing agents, the human Contact had to be made with caution and monitored in a controlled environment to avoid repeated contact led to undesirable results. The toxic properties of the glycols also made the elimination of unusable parts from glycol compounds to a complicated and necessarily costly process.

In addition, the glycol-based polish will continue to dry on the polishing tool during the normal polishing process ^

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off, although. it tends to dry out less quickly than that Water based agents. This is a problem in particular when an extensive fine polishing process is carried out becomes, and undesirable liquid additives are required to complete the polishing process. Also point to glycol based polishing agents have a tendency to react with certain polished 'surfaces, to form stains and to attack them, if they are not rinsed and washed off immediately. This imperfect effectiveness seems to explain why on Glycol-based suspensions often present exceptional difficulties in removing polished metal surfaces.

In addition to the liquid suspension media deficiencies of the existing abrasives noted above further deficiencies in connection with the common polishing material were recognized. For example, it was common to use an abrasive Made of aluminum oxide or alumina with a nominal grain size of 3 microns or less in classic fine polishing processes to use. Nevertheless, it was observed that agglomerates are contained in the clay, so that the effective particle size of the abrasive grows undesirably. The result is that the use of such agglomerated alumina can result in a scratched surface after polishing, so that then for After polishing, an even finer abrasive should be used to obtain a relatively scratch-free surface.

To remedy the above deficiencies and inadequacies is that Object of the present invention, which essentially relates to

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an improved, non-toxic, liquid fine polishing agent, which contains a relatively fine-grained, abrasive polishing dust, which is truly in a glycerine-based, through a carboxyl-polymethylene polymer thickened medium is suspended, and in which the glycerin is at least 25% by weight of the mix. While this is the main object of the present invention, it is another The aim of the invention is a permanent fine polishing suspension based on glycerine to be provided, which does not dry out during the polishing process.

The invention also aims to provide a glycerine-based fine polishing suspension which the material to be polished does not attack.

Another object of the invention is to propose a new process for producing such suspensions.

Further objects and advantages of the invention can be derived from the following description.

The fine polishing agent of the present invention is particularly a suspension of a relatively fine (with a grain size of less than 5 microns) abrasive polishing material in a glycerine-based medium in which less than 1 part Polishing material compared to 5 parts of solvent is included, so that the proportion of polishing material is less than 20 percent by weight of the whole mix.

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The polishing material used can contain aluminum oxide, diamond dust / silicon carbides, silicates and others of the desired grain size in one of the possible variants, with aluminum oxides usually in calcined form because of their availability, suitability and relative Wohlfei as well as their occurrence in usually calcined form the preference is given. In the case of using conventional calcined alumina, as well as when this is present in the nominal grain size required for fine polishing, there is a tendency to agglomerate due to the caking of the common particles. This leads to a substantial increase in the effective grain size of the polishing material beyond the desired one, namely to one of more than 15 to 30 microns. Polishing operations with such 'conventional clay therefore often lead to scratched inadvertently finish, which makes re-polishing with a finer clay necessary to obtain the desired _v finish "such material is therefore, and the additional polishing often compels" it is preferable to use calcined alumina in de-agglomerated form. This is commercially available in a form under the trade name "Baikalox." As mentioned, de-agglomerated, calcined alumina consists of: a part of alumina of nominal particle size and some agglomerates thereof, but in which the agglomerates weigh substantially at a grain size of 4 microns or less. Thus, such de-agglomerated clay is practically inherently finer in particle size. Moreover, the remaining agglomerates of 4 microns or less are only loosely cohesive so that they tend to lose their size during the polishing process iter to shred. When using them

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the result is a largely scratch-free surface, which can be achieved without the need for an additional polishing step. Indeed, the use of it does such de-agglomerated clays in conjunction with the new invention Suspension is an unexpectedly positive addition that produces the best results.

The glycerin-based medium of the invention essentially consists of glycerine and water, the proportion of glycerine being at least 25 percent by weight of the total solution to achieve the desired To achieve suspension · ^ and anti-drying properties. Regardless of the fact that the desired viscosity of the medium can even be achieved by means of an even higher concentration of glycerine up to the point of 100 percent glycerin, such are usually undesirable because it has been found that among the there is sufficient glycerine present in most conditions, even if it is present in lesser proportions by weight than water. This is desirable in view of the higher cost of glycerin compared with that of water. This is in contrast to comparable, Glycol-based polishing suspensions, which contain more parts by weight of glycol than water in the finished suspension require.

The glycerine base does this especially with fine polishing agents desired suspension medium. A glycerine-based suspension is better than a glycol- or water-based suspension, because it retains its viscosity during the polishing process thanks to the lower vapor pressure of the glycerine and its

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higher hygroscopy. In addition, the glycerine represents differently than the suspensions based on glycol, especially the general glycols such as ethylene glycol, are a non-toxic base material. This is often required in light of fine polishing operations human contact as well as the problems and costs involved in the disposal of toxic polishing waste.

What remains is the glycerol-based suspension according to the invention because of their significantly · · lower vapor pressure compared to most glycols and their significantly higher in use Hygroscopy in the frictional heat generated by the polishing process remains fluid and functional for much longer, even if appropriately lower proportions than glycol can be used. In addition, glycerine has a higher lubricating effect than oil, while it is "easily" soluble in water for cleaning and removal In contrast to glycol, glycerine is essentially impertinent, so that it can be used on polished surfaces without attacking them can remain for a long time, while at the same time it is viscous enough to adhere to the surface of the iM.pp tool.

In addition to the suspension components mainly according to the invention Glycerin and water it is also desirable to provide these with a small number of thickening agents in order to * to ensure durability and homogeneity. Thanks to the viscous In the nature of the glycerine, only a small amount of thickening agents is used to help keep the abrasive particles in suspension keep.

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The thickening agent can be a high molecular weight carboxy-polymethylene polymer such as that available from GF Goodrich Chemical under the Haridels name Carbopol 941. The Carbopol 941 described in this company's Service Bulletin GC-36 is a commercially available, water-soluble carboxylic vinyl polymer having the following physical properties: Appearance: Flaky, acidic, white powder. Bulk density: Approx. 13 pounds / cubic foot
Density: 1.41

Moisture content during shipping: Maximum 2% moisture saturation at room temperature and relative humidity of 50%: 8%
Ph value of a 1% water solution: 3

The Carbopol 941 is supplied as a dry, flaky powder, which should be carefully distributed in the carrier liquids by suitable mixing methods. In addition, it does this Neutralizing the acidic nature of the polymer with an organic or inorganic neutralizing agent or a base Optimally fast thickening with a minimal need for Carbopol. Suitable gels can also be formed with glycerin-based media by using a larger amount unneutralized polymers. This requires longer and slower mixing until the desired thickening is achieved.

The neutralization is carried out using a base such as sodium hydroxide, Ammonium hydroxide or other inorganic bases, or alternatively with one of the organic bases, such as di-tisopropanolamine., tri-

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Ethanolamine o.a. carried out. The so the mixture of glycerin solution Base added to Carbopol causes the neutralization to take place with thickening.

The abrasive powder to be suspended is either dispersed in water, water / glycerine or glycerine, which then becomes a separately formed gel is added and mixed in completely to obtain a permanent suspension.

The suspension obtained is mainly as desired from a de-agglomerated alumina polishing powder, which is converted into a carboxyl-polymethylene polymer which has been neutralized or not thickened, glycerine-containing medium is suspended. Which is so in the neutralized suspension The adjusting pH is between 7 and 8 and higher if an excess of base was added. The pH of the non-neutralized Suspension ranges from 4 to 5 and depends on the type of abrasive used in the formulation. Depending on the type of polishing process to be carried out and the material to be polished, a suspension with a PH value can be adjusted by further additives, if this is necessary.

It has been found that the use of the de-agglomerated clay in connection with the hygroscopic admixtures leads to a polishing agent which is unusual on the lapping tool holds and gives a remarkably smooth, scratch-free finish.

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Having described the invention, the following examples are provided: to set forth some of the different forms that the invention can take, as well as some methods of making to achieve the permanent suspension according to the invention.

Example 1:

Using a Waring-type high speed shear blade mixer, 105 grams of the agglomerated clay (1 micron nominal Particle size) mixed into 300 cm of distilled water and set aside. In another mixer were under high Shear treatment 1.5 g of Carbopol 941 dispersed in a mixture of 200 cm of glycerine and 100 cm. This mixture was then neutralized by adding 15 cm of a 12 percent by volume tri-ethanolamine solution to form a thick gel or Slime. The initially prepared powder / water slurry was then added immediately and added to the gel to ensure that it was even Suspension of the clay in the liquid. The pH value the final suspension was 7.0 to 7.2. Example 2:

The same procedure was followed as in Example 1 except that 105 grams of de-agglomerated clay of 3 microns nominal particle size was added. The resulting pH was 6.4 to 6.8.
Example-3:

Using a heavy duty blade mixer of the type Waring, 105 grams of de-agglomerated clay (nominal size 0.3 microns) was mixed into 300 cm of distilled water. In one another container was mixed with 2 g of car-

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bopol 941 dispersed in 100 cm of water and 200 cm of glycerine,

whereupon the mixture with 20 cm of a 12 percent by volume aqueous Tri-ethanolamine solution was neutralized / to form a thick gel to obtain. The powder / water mixture was then added immediately to form an even, permanent suspension in the gel mixed in. The addition of a larger amount of Carbopol resin, assumed a more viscous suspension than that described above. The pH of this suspension was 7.2 to 7.6. Example 4:

This example uses a premixed gel described. This example also describes the use of a low speed shear propeller type mixer in conjunction with the Carbopol.

Using a 2 inch 3 blade propeller mixer on one. rotational speed from 1200 revolutions per minute are 2.25 g of Carbopol 941 in 900 cm of distilled water ". The mixture became approximately Immobilized for an hour to allow the Carbopol resin to wet and dissolve. After soaking the blender started again, whereupon 27 cm of a 12 percent aqueous Tri-ethanolamine solution was added to the mixture to help with neutralization of the resin to achieve a clear, thick gel. The mixture was then in a storage container for later Given use.

Using a heavy duty shear mixer, the weight was 118 grams Alumina (nominal particle size 3 microns) in a mixture of

3 3

100 cm of water and 200 cm dispersed. This mixture was then

3
300'.cm dels' above-described, prepared gels using

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of the slow-running shear-propeller mixer at 1200 revolutions. The suspension obtained had excellent consistency and flow properties. The suspension produced by this preparation process - using a slow-running Seher mixer to prepare the Carbopol gel and again while mixing the gel and powdered rice - was more viscous than the suspensions described above and required over 1/3 more Carbopol -Volume units. This phenomenon was essentially attributable to low shear mixing. The pH of this suspension was 7.2 to 7.6.
Example 5:

In the last example, a premixed gel was prepared, albeit in this example the glycerol / water ratio was previously set for each of the mixing operations.

A 2-inch 3-blade propeller was used at one speed from 1200 revolutions per minute 5 g Carbopol 941 in a 1000 cm mixture of 1/3 glycerine and 2/3 water (volume ratio) dispersed. The dispersion was left to wet through for about one Hour, after which the mixer started again and the Mixture with 60 cm of a 12 percent by volume aqueous tri-ethanolamine solution was neutralized, resulting in a very thick, clear gel.

In a high-performance shear mixer, 118g of alumina (nominal Particle size 3 microns) dispersed in a solution of 1/3 glycerine and 2/3 water (volume ratio). This pulp then turned to 300 cm of the premixed gel added .. and mixed by hand,

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ORIGINAL INSPECTED

This was followed by a short homogenization process using a mixer. A very uniform, thick suspension resulted , the pH of which was 7.0 to 7.2.

Example 6:

This example is given to show that it is permanent Grinding suspension with non-neutralized Carbopol formulations can be made if so desired.

Using a high-performance shear mixer, 2 g of Carbopol were added dispersed in 400 cm of a 50 percent by volume aqueous glycerine solution. The dispersion was then ± ή another container and then for two hours using a 2-inch propeller mixer Stirred continuously at over 300 revolutions per minute. The Carbopol resin thickened by the action of hydrogen bonding in connection with glycerine. After two hours the thickened solution is returned to the high-performance mixer, whereupon 70 g of de-agglomerated clay (particle size nominal 1 micron) into the thickened mixture by mixing for several minutes at low mixing speed (between 4500 and 6000 per Minute under load). A very viscous dispersion with a pH of 4.5 to 5 was achieved.

Although in this partial example in comparison to the other preparations If a higher proportion of glycerine was used compared to water, lower proportions of glycerine could be used in conjunction with non-neutralized compounds are used and still satisfactory results can be achieved. For example · could even with one Glycerine proportion by weight of less than 30% of the total compound

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with the same amounts of the other components one is insufficient * neutralized compound can be obtained.

Example 7:

This example is intended to demonstrate the use of a premixed gel, as well as another amine, diolsopropanol amine, as a neutralizing agent to show.

A prepared solution of 1/3 glycerine and 2/3 water (volume ratio) was mixed as a basis for the preparation of suspensions. 1000 cm of this was taken, and this 5 g of Carbopol 941 added using a propeller stirrer. This mixture was left to rest for about an hour, then again was mixed to completely distribute the wetted Carbopol. Then, while stirring, the solution was added by adding 60 cm of a 10 percent by volume aqueous solution neutralized by di-isopropanolamine to the carbopol / water / glycerine solution. A thick gel formed immediately.

A suspension was de-agglomerated by admixing 118 g Alumina (nominal grain size 0.3 micron) in 300 cm of the above

3 th glycerine / water solution prepared, whereupon this in 300cm des the aforementioned gels were mixed in. The mixture was mixed first by hand and then briefly in a high capacity shear mixer mixed to a homogeneous, creamy consistency. The pH of this "suspension" was 7.6 to 8. There appeared to be no difference in the suspension properties between this suspension and eir ner formulated with tri-ethanolamine as a neutralizing agent .zu be.

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Example 8:

This example is intended to show another method of making a Polishing suspensions according to the invention show which is particularly desired when using relatively high concentrations of the Carbopol resin to be needed. Such high concentrations can be found in the manufacturing process, where according to the examples given first a gel is prepared, which is only used to 50% or a partial amount of the final volume, or if relatively high concentrations of carbopol to suppress the effect ". high ion concentration in certain abrasive materials to be needed.

Following this example, 3 g of Carbopol 941 are put into a mixture

3 3

of 200 cm of glycerine and 400 cm of water using a Propeller mixer dispersed. To this dispersion, 75 grams of 0.06 micron nominal particle size clay was added to get a fairly thick, creamy mixture. This mixture was placed in a high speed shear mixer, whereupon 36 cm eienr 10 percent solution of di-isopropanolamine during the Mixing were added, which as the last step of the process the Carbopol neutralized. A very even suspension was achieved.

In the event that very fine-grained clay (less than 0.1 micron nominal grain size) used in the manufacture of polishing agents becomes, it is very difficult »such particles in liquids appropriately dispersed, and they also characteristically contain a relatively large amount of impurities

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by sulfate ions, which are harmful in Carbopol formulations, unless a relatively high concentration of Carbopol was used. The technique of this example is useful in the production of such problematic compounds, as it is ultimately the thickening and mostly the dilution state of the Formulation finished.

The weight percent of the constituents of the suspension examples above are shown in the following table.

Table Ϊ

Weight components in percent

example

No. Alumina Water Glycerin Carbopol Amine

1 and 2 13.6 53.4 32.5 0.19 0.19 3 13.5 53.5 32.3 0.25 0.25 4th 15.1 52.4 32.3 0.10 0.12 5 14.9 52.8 31.9 0.19 0.23 6th 13.3 38.2 48.1 0.38 0.0 ■ 7th 14.9 52.8 31, 9 0.19 0.23 8th 9.8 56.5 32.7 0.39 0.47

As can be seen from the above description and table, exist the examples of the polishing agents according to the invention made from 9.8% to 15.1% alumina with a nominal grain size of less than 3 microns; from 38.2% to 56.5% water; from 30% to 48.1% glycerin; from 01% to 039% carboxy-polymethylene polymer; and from 0 toO, 47%

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organic amines (percentages in percentages by weight of the total mixture). Considering these examples which use a base to neutralize the carbopole, the ranges are reduced from 0.8% to 15.1% alumina; from 52.4% to 56.5% water; from 31.9% to 32.7% glycerin; from 0.10% to 0.39% carboxylic polymethylene polymer; and from 0.12% to 0.47% organic amine bases (again in percent by weight).

In the above examples in which the Carbopol neutralized was, only a weak extract of a neutralizing agent was used, which the suspensions in the neutral or left in a very weakly alkaline state. The organic neutralizing agers were usually given preference before the stronger inorganic bases, since the organic agents do not lead to ion concentrations in the suspensions, which are harmful when polishing electronic and semiconductor substrates could be.

The following additional examples deal with the use and "formation of polishing agents according to the invention as compared to conventional agents."
Example 9:

A polishing machine from the -lyp Büehler Minimet '. Was. Used for a sample polishing used. The polished specimens were small single-diameter cylinders made of weldable steel, which at one end with was polished to the tested agent. The patterns were about the same Periods of time, polished with the same pressure and on the same polishing pad and then under 20-fold and 40-fold magnification

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compared with obliquely reflecting lighting.

Two polishing samples were prepared here, in which first one relatively coarse 6 micron finish using diamond paste. The samples were then individually on separate, similarly pre-moistened polishing pad polished, a polishing agent was used in one pattern, which consisted of conventional calcined alumina nominally 0.3 microns in size, and which in a medium consisted of mainly Ethylene glycol and water with more weight percent glycol than water existed, and which with neutralized Carbopol was thickened; the agent according to the invention, provided in Example 3 above, was used on the other sample with de-agglomerated, calcined clay of 0.3 micron nominal grain size is used.

Both samples were polished with the appropriate agents for four minutes and then washed and viewed under a microscope. The finish on the pattern, which had been polished with the agent according to the invention, was of high quality with only one Scratches on. the background polish while the other pattern is many Had scratches covering the entire surface. This scratched pattern was then left on the pillow for 55 seconds, which contained the agent according to the invention, polished, whereupon it received the same quality finish as the other sample.

Five minutes after the polishing tests, the polishing pads were compared ^ The pillow with the conventional means was too dry

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started and was baked together; the pillow with the agent according to the invention, on the other hand, was still very damp and it was easy to wash the agent off the pillow.
Example '10:

Here an attempt was made to determine the relative corrosion properties of the agent according to the invention - compared to a conventional, alumina polishing suspension based on glycol / water

determine. In particular, a sample amount of 2 cm of the corresponding Example 7 prepared agent according to the invention applied to the surface of a polished aluminum plate. One corresponding amount of the agent, which ethylene glycol instead used by glycerin was also applied to the surface of the plate.

The patterns would be left on the aluminum for 1-9 hours and then washed in hot water and then dried the plate. The pattern based on ethylene glycol had visibly violently etched the aluminum plate, while the pattern according to the invention only had caused a faint etching appearance. In fact, it has been found that even 30 seconds of contact with ethy- - Polished metal surfaces that are sufficient for polishing agents based on len-glycol to touch so strongly, -; that polishing is necessary, to obtain a desired mirror-like finish; such a brief contact with the agent according to the invention did not result in any: such etching.

For some applications it can be advantageous to use suspensions; mi ^: t to have either a very high or a very low pH value .. \.-_ ~. =

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This can be achieved with Carbopol-neutralized suspensions according to the invention, as long as the pH value is set, after the Carbopol gel is neutralized / and before the abrasive Mixture was finally added to obtain the suspension.

In the above Examples 1 to 8, alumina in various shapes and grain sizes were used as abrasive substances. While these are generally preferred because of their availability, other abrasive substances of suitable grain size can be used instead can be used.

As noted earlier, the suspensions according to the invention are used in Fine grinding of such materials as optical components, plastics, Metals, precious stones, semiconductors or whenever an extremely smooth and essentially scratch-free surface is required is needed. When polishing plastics and optical parts made of plastic, in particular the suspensions j this invention, which use de-agglomerated clay, preferred, since plastic is a relatively soft material that can be scratched very easily, even if the agglomerates are loosely held.

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Claims (7)

Applicant: La Pierre Synthetique Baikowski, S.A. • 13, Avenue Des Romains / 74001 Annecy Cedex, France Claims M .J An essentially non-toxic, liquid .fine-polishing- medium with non-drying properties, in which a fine, abrasive polishing dust with a nominal grain size of less than approx. 5 microns, essentially permanently in a viscous liquid is suspended which comprises glycerine and a thickening carboxy-polymethylene polymer agent, characterized in that the polishing dust makes up less than about 20 parts by weight and the glycerine makes up at least about 25 parts by weight of the total mixture. 2. polishing agent according to claim 1, characterized in that the polishing dust is a de-agglomerated alumina powder with a nominal Grain size is less than 3 microns. 3. polishing agent according to claims 1 and 2, characterized in that that the liquid medium also contains water, the proportion by weight of water in the total mixture being greater than that of glycerine. 4. polishing agent according to one of claims 1 to 3, characterized in that that it additionally contains a neutralizing agent from the group of inorganic hydroxides and organic amines. 5. polishing agent according to one of claims 1 to 4, characterized 130009/0663 r —- r-— ~ - ORIGINAL INSPECTCSD indicates that the polishing powder is a de-agglomerated / calcined Alumina powder with a nominal grain size of less than 5 microns, which is with a proportion of about 9.8 to 15.1 percent by weight is present, that water with a proportion of approx. 38.2 to 56.5 percent by weight, glycerine with a Share of about 30 to 48.1 percent by weight that carboxyl-polymethylene polymer with a proportion of about 0.1 to 0.39 percent by weight and the organic amines with a proportion of 0 to 0.47 percent by weight are present. 6. polishing agent according to one of claims 1 to 5, characterized in that that the polishing powder is a de-agglomerated, calcined Alumina powder with a nominal grain size of less than 3 microns, which is about 15 percent by weight it is present that water with a proportion of approx. 53 percent by weight, glycerine with a proportion of 32 percent by weight, that carboxyl-polymethylene polymer with a proportion of about 0.2 percent by weight and the organic amines are present with about 0.2 percent by weight. 7. polishing agent according to one of claims 1 to 6, characterized in that the polishing powder is a de-agglomerated, calcined alumina powder with a nominal grain size of less than 3 microns, which is present in a proportion of about 13 percent by weight that Water with a proportion of approx. 38-56 percent by weight, glycerine with a proportion of approx. 30 to 48 percent by weight and that carboxyl-polyethylene polymer with a proportion of less than 1 percent by weight are present. 130009/0663